This invention relates to a universal modular tread and riser unit for mounting on a stairway stringer for supporting a tread and a riser of a stairway, which unit includes structure for accommodating a stairway of any pre-selected rise and length. Once the rise and length of the stairway is selected, all of the units used with the stairway can be sized at one time for forming a stairway having the pre-selected rise and length.
Metal channels have been used for forming a stairway. See for example, U.S. Pat. No. 4,635,416 to Ayala. With this apparatus, each channel must be positioned individually to accommodate a stairway having a pre-selected rise and length.
U.S. Pat. No. 4,709,520 to Vochatzer shows stair brackets that must be individually positioned to accommodate a stairway of pre-selected rise and length. Guide tabs are provided to locate the bracket on a stringer having a pre-selected slope.
Other modular stair forming units are shown in U.S. Pat. No. 5,293,722 to Reimann and U.S. Pat. No. 5,806,254 to Bennett.
From the above it can be seen that what is needed is a universal modular tread and riser unit for mounting on a stairway stringer, which unit includes structure for accommodating a stairway of any pre-selected rise and length. Once the rise and length of the stairway is selected, it is desirable to have all all of the units used with the particular stairway sized easily at one time. It is further desirable to have the capability of mounting all of these units to a stairway stringer with the unit properly positioned on the stringer to have the treads horizontal and the risers vertical.